There has been proposed an image forming apparatus which employs an imaging substance such as color toner or black toner to form color or monochrome images on a recording medium (e.g., see JP-A-2001-83750). The imaging substance used in such an image forming apparatus is a consumable supply. Thus, images cannot be formed when no remaining imaging substance is available. In this context, when it is detected that no remaining imaging substance is available, a warning is indicated.
For example, JP-A-2001-83750 discloses an image forming apparatus that displays a message (warning indication), “No yellow toner available,” when it is detected that yellow toner is not available. In addition, when it is detected that yellow toner is not available, a message “Copying in monochrome available” is also displayed on the operation screen together with the above-described message.
However, such a warning indication as provided for the remaining level shortage of a consumable that is not necessary to perform a function desired by a user would lead to a user's operating comfort being compromised or cause the user to feel frustration. For example, a user who desires color printing requires a warning indication that no color toner is available. However, another user who desires not color printing but monochrome printing would often feel frustrated of the warning indication that no color toner is available.
Further, there exists an image forming apparatus with a small display screen which can display only one or two lines of text due to the limited design space, etc. When a warning indication is displayed on such a small display screen, other information cannot be displayed. For this reason, a user who uses an image forming apparatus with a small display screen tends to further feel frustrated of an unnecessary warning indication every time the warning indication is displayed.